1. Field of the Invention
The present invention relates to a method and a device for image processing as well as to a computer-readable recording medium.
2. Description of the Related Art
Some conventional types of image forming apparatuses have a toner saver function of printing an image with a reduced amount of colored material such as toner than normal. Some types of image forming apparatuses have a multiple-up (N-up) printing function of printing an image containing multiple pages (N pages) of an original document on a single sheet of paper. Although both the toner saver function and the N-up printing function allow reducing toner consumption per a page of the document, if the toner consumption is excessively reduced by the toner saver function, a problem of a decrease in character legibility can arise. A configuration that applies an optimum toner saving ratio depending on a character size to solve this problem is known.
For example, Japanese Laid-open Patent Application No. 2014-32436 discloses a configuration for applying an appropriate toner saving ratio by analyzing a size of a character in data representing an original document image and determining a toner saving ratio based on the character size.
However, conventional techniques such as those noted above are disadvantageous in the following respects. The conventional configuration that applies an optimum toner saving ratio depending on a character size does not take difference in structure and/or color between individual characters into account. For this reason, it has been a problem with the conventional techniques that legibility of a character of relatively complicated structure or light color is impaired by toner saving and that toner consumption of a character of relatively simple structure or thick color cannot be reduced satisfactorily. This problem can arise also with the technique disclosed in Japanese Laid-open Patent Application No. 2014-32436. This is because the toner saving is carried out without taking difference in structure and/or color between individual characters into account.
In view of the above circumstances, there is a need for a technique that allows reducing an amount of toner consumed in printing characters appropriately while avoiding reduction in legibility of the printed characters.